1. Field of the Invention
The present invention relates to powertrains of work machines, and, more specifically, to integrated braking systems for such machines.
2. Description of the Related Art
For many years, work machines have incorporated brake assemblies within their powertrain and, more specifically, adjacent the torque-carrying shafts spaced from the wheels for such vehicles. Typically, these brake assemblies comprise a series of interdigitated annular plates that are respectively connected to a housing in which they are positioned and to a torque-carrying power shaft. The brake assemblies are activated by an external piston that forces the brake disc plates together to provide a retarding force between the housing and the torque-carrying shaft. Because the friction plates are positioned within the housing, a system for lubricating the plates and for dissipating excess heat must be employed. Typically, such cooling system includes a pump recirculating powertrain lubricant through a heat exchanger and through the friction plates for the unit.
In recent years, there has been an increased emphasis on minimizing parasitic losses within the entire system of a work machine. For such a machine, it has been proposed to vary the amount of coolant and lubricant flowing through the friction plates so as to minimize heat generated by the assembly.
In the past, it has been proposed to control the flow through the friction plates by means of a valve and a control system with logic sensing when the clutch plates are disengaged to minimize the lubricant flow through the assembly. While this is one attempt to minimize the expenditure of energy, it requires a complicated set of hardware and of control logic to achieve the end.
What is needed in the art, therefore, is a cooling system for the brake assembly of a powertrain that minimizes and simplifies the function of reducing lubricant flow during disengaged operation.